A New Study Rejects Global Warming Alarmists' Favorite Argument

Posted on: Friday, November 24, 2017By: GabriellaComments

Princeton University and National Oceanic and Atmospheric Administration scientists have presented evidence against a favorite argument
of researchers trying to prove a link between man-made global warming and hurricane activity.

The study found
the lull in major Atlantic hurricane frequency from 2005 to 2015 was brought on by "a weakening of the Atlantic Meridional Overturning
Circulation (AMOC) inferred from ocean observations."

However, researchers also found evidence "suggesting the decline of the Atlantic major hurricane frequency during 2005–2015 is not likely
due to recent changes in anthropogenic sulfate aerosols."

This is in direct conflict with a theory advanced by some of the most prominent climate scientists who claim air pollution from cars
and power plants has kept hurricane activity in check, despite warming ocean temperatures.

"Instead, we find coherent multidecadal variations involving the inferred AMOC and Atlantic major hurricane frequency, along with indices
of Atlantic Multidecadal Variability and inverted vertical wind shear," reads the study, led by scientist Xiaoqin Yan.

"Our results provide evidence for an important role of the AMOC in the recent decline of Atlantic major hurricane frequency," Yan and
his colleagues wrote.

Prominent climate scientists, including Penn State’s Michael Mann and MIT’s Kerry Emanuel, have argued for years that "sulfate aerosol
pollution" is the main reason why Atlantic hurricane activity was so muted in the 1970s and 1980s.

Atlantic hurricane frequency began increasing in the mid-1980s, peaking around 2005. In a 2006 study, Emanuel and Mann attributed the rise in
hurricanes to clean air regulations that kept more climate cooling pollution particles out of the atmosphere.

"A debate continues about why the 1970s and ’80s were relatively quiet in the Atlantic," Emanuel told The Washington Post in September.

"Some believe that it was the consequence of a natural climate oscillation called the Atlantic Multi-decadal Oscillation (AMO), while
others, including me, think it was mostly a consequence of sulfate aerosol pollution," Emanuel said.

That theory hasn’t been totally accepted by scientists, and Yan’s study adds weight to the counter-argument that ocean circulation plays
a greater role in hurricane activity.

"Directly observed North Atlantic sulfate aerosol optical depth has not increased (but shows a modest decline) over this period," Yan
wrote, suggesting the decline in hurricane activity was not caused by efforts to improve air quality.

Instead, Yan says the AMOC, an ocean circulation pattern, is more closely related to the increase and decrease in Atlantic major hurricane
frequency. The AMOC switched from a warm phase to a cool one around 2005, taking hurricane activity down with it.

Yan expects "changes in the Atlantic major hurricane frequency in the next decade would be closely linked to future AMOC changes."